This invention relates to a device for depositing sliver into a coiler can, particularly a flat coiler can having an elongated horizontal cross-sectional shape. Further, the invention concerns in particular a coiler can used in conjunction with a draw frame or a carding machine, wherein the sliver is deposited into the coiler can in coils and the free sliver end hangs from an upper can edge in a downward orientation at the outside of the coiler can.
In practice, the sliver is advanced in a sliver guiding channel of a rotary coiler head and fills, in coil layers, a coiler can which is positioned underneath the coiler head. During the filling operation the flat coiler can is horizontally reciprocated. When the coiler can is full, it is moved a predetermined distance from a zone underneath the coiler head. During this occurrence the sliver is still connected to the coiler head and extends to the uppermost coil layer in the coiler can. Subsequently the sliver is severed, for example, by means of a mechanical severing device. In this manner, a free sliver end is obtained which, because of the significant distance between the coiler can and the coiler head, has an appreciable length as it hangs down along the outside of the coiler can. In such a process first the final length of the free sliver end is obtained and subsequently the sliver is severed.
It is a disadvantage of the above-outlined conventional arrangement that an accurate length of the free sliver end cannot always be obtained. It may happen that the overhanging sliver end is excessively long for the subsequent processing during which the sliver end has to be accurately grasped to ensure that it is securely advanced to a processing apparatus. Further, the exact positioning and orientation with respect to the coiler can in case of a long sliver end is not ensured.
German patent document No. 195 48 232 to which corresponds U.S. Pat. No. 5,621,948 discloses an apparatus wherein the draft of a draw frame situated upstream of the sliver outlet opening is briefly increased such that a reduced cross section at a location of the sliver bundle is obtained. The combined sliver subsequently produced from the sliver bundle runs, with the reduced cross-sectional location, through the entire sliver channel of the coiler head up to the outlet opening. When the location of reduced thickness has reached the deflecting edge at the outlet of the sliver channel, the sliver is severed by virtue of the fact that the coiler can is moved away horizontally. Stated differently, the distance between the sliver outlet opening and the uppermost coiler layer in the coiler can is increased such that the sliver ruptures at the location of reduced thickness without the need of an additional severing device. Upon initiating the sliver severing process, one of the narrow walls of the flat coiler can is situated approximately below the severing edge. If the middle of the flat can were positioned below the severing edge, then upon moving the can away, additional deposited sliver coils would be dragged along which would be an undesired occurrence. In particular, the sliver end would be situated on top of the uppermost coil layer of the sliver rather than hanging laterally outside the coiler can. When the location of reduced thickness in the sliver is situated on the deflecting edge and the narrow wall of the coiler can is positioned below the deflecting edge, the coiler can is moved away, resulting in an excessively short free sliver end at the coiler can. A short sliver end is not adapted for being automatically grasped and admitted to the feeding device of an after-connected processing machine, for example, a spinning machine.
It is an object of the invention to provide an improved device and method of the above-outlined type from which the discussed disadvantages are eliminated and which, in particular, is capable of producing, in a simple manner, a free sliver end with a sufficient and accurately predetermined length.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the apparatus for lengthening, to a determined extent, a free sliver end portion hanging on an exterior face and from an upper edge of a can containing sliver deposited in coils, includes a device for grasping and firmly holding the free sliver end portion, and an arrangement for moving the grasping device and the can away from one another for pulling an additional length of sliver from the can to lengthen the free sliver end portion.
Thus, first the sliver is severed between the coiler can and the outlet opening of the coiler head and subsequently, according to the invention, the precise, predetermined length of the sliver end is produced. According to the invention, between the end of the hanging sliver and the coiler can a defined relative motion is obtained. In particular, the sliver end is fixed and subsequently, the coiler can is horizontally shifted. Thus, the end portion of the sliver is lengthened by the removal and linear orientation of a sliver coil from the uppermost sliver layer of the sliver deposited in the coiler can. In this manner, a free sliver end with an accurately predeterminable length is obtained. Further, the position of the sliver may be precisely determined in relation to the can wall on which it hangs, so that in this manner too, a further processing of the sliver is improved. By virtue of the exact length and position of the free sliver end an automatic start of the successive machine is feasible.
The invention has the following additional advantageous features:
Upon severance of the sliver the distance between the outlet end of a coiler head which deposits the sliver into the can in coils and a can wall closest to the coiler head is about 30 to 90 mm.
After severing the sliver, the extended length of the free sliver end portion corresponds essentially to the distance between the can wall closest to the coiler head and the sliver outlet opening of the coiler head.
The period during which the free sliver end portion is firmly held is determined by the control device of the sliver producing machine at which the sliver is deposited by the coiler head.
The extended free sliver end portion has a length of about 90-140 mm, preferably between about 120-130 mm.
The device which grasps and firmly holds the free sliver end portion is a mechanical clamping element.